1. Field of the Invention
The present invention relates to an electrical connection box mounted in, for example, an automobile.
2. Description of the Related Art
As vehicles, e.g., automobiles, are expected to meet increasing market requirements for comfortable riding, they tend to require use of increased electrical compartments, such as an audio system, navigation system, TV set, power antenna, air conditioner, rear window heater, seat heater, power seat, suspension hardness control device, etc.
The electrical compartments are supplied with electric power from wire harnesses or the like through an electrical connection box that is located near a battery in an engine compartment or a pedal attached to a driver""s seat. In some cases, excessive current may flow in the electrical connection box if the vehicle body and the wire harnesses or the like are shorted or if a load such as a motor goes wrong from any cause. The electrical connection box is mounted with a large number of electrical components, such as fuses to cope with such trouble and relays that control power supply to the electrical compartments in association with various operating switches.
As is schematically shown in the partial sectional view of FIG. 11, the electrical connection box 1 comprises a lower casing (not shown) fitted with the relays, an upper casing 2 fitted with at least two fuses, formed with connector housings 2a, 2b that can be fitted with a connector C of wire harnesses on the vehicle body, and attached to the lower casing, an electrically insulating wiring board 3 located between the lower casing and the upper casing 2 and having wires laid in a desired shape on either side thereof, and pressure connection terminals (not shown) for electrical connection between the wires and the electrical components and connection between the wires. The electrical connection box 1 further comprises at least three busbars 4a, 4b, 4c for high-current conduction on either side of the wiring board 3, an insulating plate 5 interposed between the upper casing 2 and the busbars 4a, 4b, 4c so that one of the busbars 4b is held between the plate 5 and the board 3, and the like.
The wiring board 3 is formed with laying grooves (not shown), which are a little wider than the wires and extend so that the wires can be laid in desired shapes therein. The wires are fitted in the laying grooves to be laid in a predetermined path.
In general, the wire laying operation is carried out by means of an automatic laying apparatus. More specifically, the lead of each wire is inserted into a given position in one of the laying grooves by means of the laying apparatus. Subsequently, the wire is continuously laid with one stroke in the predetermined path, and its trailer is cut. Thereafter, the wire is cut at given spots to be divided for each circuit. Further, the pressure connection terminals are driven in given positions on the wire so that they can conduct to the wire, electrical components, and external connecting terminals for the individual circuits. A plurality of electric circuits thus formed are coupled to a plurality of connectors (not shown) of the body-side wire harnesses through the external connecting terminals, individually. A projection that is formed on a part of the busbar 4c can be also coupled as an external connecting terminal to the connector C.
The external connecting terminals and the wire harnesses can be connected electrically to one another by fitting predetermined wire harness connectors (only the connector C of which is illustrated as a representative) individually into the connector housings 2a, 2b of the upper casing 2.
The electrical components mounted in the vehicle can be combined in various manners depending on the specifications of the vehicle. Accordingly, there are various electric circuits that are formed on the wiring board or busbars, corresponding to the individual electrical components. Further, there may be a lot of combinations of external connecting terminals that are led out of the upper or lower casing, corresponding to the electric circuits. Various types of upper and lower casings must be prepared if electrical connection boxes that have external connecting terminals and connector housings corresponding to the specifications of the vehicle are manufactured for the individual specifications.
In general, however, the upper and lower casings are generally formed of synthetic resin, so that molds must be prepared individually for the upper and lower casings of various specifications, thus entailing high manufacturing costs. It is to be desired, therefore, that the upper and lower casings should be designed for common use to be compatible with any electrical components mounted in the vehicle. More specifically, all usable connector housings may be formed on the upper or lower casing in advance so that unused ones can be stopped with rubber grommets G while the electrical connection box is being assembled, as shown in FIG. 11, depending on the specifications of the vehicle in which the box is mounted. Thus, the wire harness connectors can be prevented from being wrongly connected to the connector housings.
Once an operator fails to stop the connector housings to be stopped with the grommets G during the assembly of the electrical connection box, however, there is a high possibility that another operator in charge of a vehicle assembly line may wrongly connect the wire harness connectors to the electrical connection box. This is because the electrical connection box is generally located in the engine compartment of the vehicle or near the pedal attached to the driver""s seat, that is, in a position such that the operator must connect the wire harness connectors by touch without directly viewing the connector housings.
With the electrical connection box in this situation, the operator usually fails to become aware of wrong connection if he fits by touch the wire harness connectors into unstopped connector housings that should be stopped with the grommets, that is, connector housings having no external connecting terminals. Once the connectors are wrongly connected in this manner, the wrong connection can be detected only in an inspection process after the assembly of the vehicle. In order to reconnect the wire harness connectors to correct connector housings, thereafter, peripheral components must be disengaged again, so that the correcting operation requires substantial labor.
On the other hand, an electrical connection box that serves to simplify the arrangement of complicated electric circuits of an automobile comprises upper and lower casings, which are combined together with busbars and a wiring board between them. The electrical connection box is loaded with electrical components, such as relays, fuses, connectors, capacitors, diodes, control unit, PTC (positive temperature coefficient) thermistor, etc. The relays, fuses, connectors, etc. vary in size, especially in height, depending on their respective functions.
In the conventional electrical connection box, however, loading portions for carrying the electrical components are designed without giving consideration to differences in height between the components.
Modern automobiles are designed to enjoy minimized external dimensions and as wide an inside space as possible, so that room for the electrical connection box is gradually becoming narrower. Thus, in order to secure good room in the automobile, the electrical connection box is expected to be minimized in thickness, and therefore, in size.
In the electrical connection box loaded with tall electrical components, therefore, the components excessively project outside the casings, so that the thickness of the box increases. Thus, the conventional connection box inevitably interferes with body portions of the automobile.
A first object of the present invention is to provide an electrical connection box in which wrong connection of wire harness connectors can be prevented securely. A second object of the invention is to provide an electrical connection box of which the thickness can be minimized in consideration of the respective heights of various electrical components mounted therein.
In order to achieve the first object described above, an electrical connection box according to the present invention comprises first and second casings, capable of being combined with each other, and a wiring board, located between the first and second casings and having a plurality of independent electric circuits, and mounted with an electrical component. In this electrical connection box, the first and/or second casing is formed with a connector housing to be fitted with an external connector, and external connecting terminals coupled to the electric circuits and electrically connecting the electric circuits and the external connector or a checking member formed on the wiring board and capable of preventing the external connector from being fitted in the connector housing projects into the connector housing.
According to the electrical connection box described above, the first and second casings can be designed for common use without regard to the specifications of the connection box, and the wire harness connectors cannot be wrongly connected to the connector housings. Even if the electrical connection box is mounted in a vehicle or any other place where the connectors cannot be efficiently connected, therefore, there is no possibility of wrong connection of the connectors, so that troublesome reconnecting operation for the connectors need not be carried out after the vehicle is assembled.
Preferably, the electrical connection box according to the invention further comprises an insulating plate located between the first casing and the wiring board and/or between the second casing and the wiring board, and is designed so that the checking member is formed on the insulating plate in place of the wiring board.
Thus, the checking member is formed on the insulating plate that can be molded more easily than the wiring board, so that the electrical connection box can be manufactured at low cost according to various specifications without the possibility of wrong connection of the connectors.
Preferably, the wiring board has the independent electric circuits formed of wires laid in laying grooves on both the obverse and the reverse thereof.
Preferably, moreover, the checking member is an L-shaped rib formed on the insulating plate.
Preferably, furthermore, the electrical connection box comprises a control unit.
In order to achieve the second object described above, on the other hand, an electrical connection box according to the present invention comprises a first casing and a second casing combined together, with a first busbar, an insulating plate, and an electrically insulating wiring board between the casings, and mounted with various electrical components of different heights, the wiring board having thereon a wire laid in a desired shape or being fitted with a second busbar molded in a desired wiring shape. In this electrical connection box, the first and/or second casing has mounting portions for the various electrical components, each formed in the shape of an inwardly recessed groove or an inwardly projecting cylinder in consideration of the respective heights of the various electrical components or in the shape of an aperture through which an attachment portion of the wiring board for the various electrical components is passed.
With this arrangement, the thickness of the electrical connection box can be minimized in consideration of the respective heights of the various electrical components mounted in the box.
Preferably, the first and second busbars are provided with terminals in desired positions.
Preferably, moreover, the insulating plate is notched corresponding to the mounting portion.
Preferably, furthermore, the wiring board has a large number of laying grooves on both the obverse and the reverse thereof.
Preferably, the second casing is formed integrally with an extension extending sideways at right angles to the thickness direction thereof and having a control unit thereon.
The above and other objects, features, and advantages of the invention will be more apparent from the ensuing detailed description taken in connection with the accompanying drawings.